Various types of overshot tools have been designed for interconnecting and sealing between a lower tubular in a well and an upper tubular in a well. In an exemplary application, the lower tubular may have separated or may have been cut off so that the overshot tool connects an upper end of the lower tubular with a lower end of the upper tubular each positioned within the well.
U.S. Pat. Nos. 4,023,847, and 4,127,297, disclose overshot tools developed in the 1970's. U.S. Pat. No. 5,054,833, discloses a releasable overshot which is complex and has numerous parts. An overshot cutter is disclosed in U.S. Pat. No. 5,690,170. U.S. Pat. No. 6,425,615, discloses an overshot tool with a radially expandable and contractable grapple. U.S. Pat. No. 7,422,068, discloses a casing patch overshot which utilizes a wedge to expand a lower end of an upper tubular. U.S. Pat. No. 7,493,946, discloses a tool for radially expanding a tubular. U.S. Pat. No. 7,503,388, discloses an overshot retrieval tool with a slip-type overshot.
One of the primary difficulties associated with overshot tool techniques is the reliability of the mechanical interconnection and the fluid tight seal between the upper end of the lower tubular and the lower end of the upper tubular. In some applications, the mechanical connection may be adequate for a short time, but subsequently problems may exist when the lower tubular begins to separate from the upper tubular. In other applications, a mechanical interconnection is maintained, but the fluid tight seal is lost between the upper and lower tubulars, so that some fluid from the lower tubular escapes to the annulus surrounding the lower and upper tubulars, or fluid from the annulus enters the tubular at the overshot interconnection.
The disadvantages of the prior art are overcome by the present invention, and an improved overshot tool and method of interconnecting and sealing between a lower tubular and an upper tubular are hereinafter disclosed.